The present technique relates generally to a system and method for cooling a lamp and, more specifically, to a cooling technique for a short arc gas discharge lamp.
Gas discharge lamps are used in modern lighting technology including fluorescent lighting, liquid crystal displays, indicator lamps, germicidal lamps, neon signs, photographic electronic flashes, video projectors, or the like. Typically, gas discharge lamps comprise a gas filled inside a glass, quartz, or translucent ceramic arc tube. These lamps also include a pair of electrodes, which are energized to create a discharge within the arc tube to ionize the gas. The ionized gas, in turn, generates visible and/or ultraviolet light.
The performance of gas discharge lamps for video projectors depends at least partially on a relatively small arc gap (e.g., on the order of 1 mm) formed between the pair of electrodes located inside the arc tube and, also, a relatively high pressure (e.g., on the order of 100 to 400 atmospheres) of the gas filled inside the arc tube. The use of a ceramic tube rather than a quartz tube enables the gas discharge lamp to operate at higher operating temperatures within the lamp tube. In turn, the ceramic tube enables the gas discharge lamp to operate at a relatively higher vapor pressure with a commensurate reduction in the arc gap between the pair of electrodes. These advantages also lead to improvements in the spectral output of the gas discharge lamp.
In operation, these gas discharge lamps generally have temperature differentials, which can lead to stresses that reduce the lifespan of the lamp. For example, tensile stresses are predominant in the ceramic arc tube due to a large coefficient of thermal expansion in combination with a large temperature difference between a top and bottom side of the arc tube. Unfortunately, passive convective cooling of the arc tube is insufficient to reduce the tensile stresses to an acceptable level.
Therefore, there is a need for a system and method for reducing temperature differentials in the walls of a ceramic arc tube to reduce potential stresses.